Fixed Appliance On Periodontal Microecology

Objective:To observe the effect of fixed orthodontic treatment on periodontal micro-ecosystem, before and after the fixed orthodontic appliance wear, we examined the dynamic nucleatum content changes of Actinomyces viscosus (A.viscosus) in supragingival plaque, Porphyromonas gingivalis (P.gingivalis) and Fusobacterium nucleatum (F.nucleatum) in subgingival plaque, by the method of Real-time quantitative PCR. Besides, we also observed changes of clinical periodontal index, which was in response to periodontal health and periodontal micro-ecosystem.Methods:Our study selected 20 patients wearing the straight wire appliance into our observation and chosed the right maxillary first molar (16), the left maxillary central incisor (21), the left mandibular first molar and the right mandibular central incisor (41) as index teeth. The index teeth were checked the plaque index (PLI), gingival index (GI) and probing depth (PD), Pre-treatment and treatment of 1,3 months. At the same time, the supragingival plaque and the subgingival plaque of the index teeth were collected for DNA extraction. Then Real-time quantitative PCR were used to detect the nucleatum content of A. viscosus, P.gingivalis and F.nucleatum.Results:1. Periodontal indexes:One month in treatment, the GI, PD of the right maxillary first molar and the PLI, GI of the right mandibular central incisors were significantly higher than pre-treatment level (p＜0.0167). Three month in treatment, the PLI, GI of the right mandibular central incisors were decreased to the pre-treatment level, while the PLI, GI, PD of the right maxillary first molar significantly increased than the pre-treatment level (p<0.0167). The PLI, GI, PD of the other index teeth showed no significant change (p> 0.0167), one and three month in treatment.2. Microbiological indexes:One and three month in treatment, the percentage of A. viscosus in left central incisors supragingival plaque were significantly higher than the pre-treatment level (p<0.0167). One month in treatment, the percentage of Rgingivalis in the upper right first molars subgingival plaque were also significantly higher than the the pre-treatment level (p<0.0167). However, there were no significant changes of F. nucleatum content in the all four index teeth, one and three month in treatment.Conclusions:1.Fixed appliance damaged the periodontal microflora balance, caused the percentage of Porphyromonas gingivalis significantly higher in band teeth subgingival plaque and the percentage of Actinomyces viscosus significantly higher in supragingival plaque. There is the riskof periodontal tissue destruction and the of enamel demineralization.2.The impact of fixed appliances on oral health and periodontal tissues health is obvious on the band teeth, may be temporary on the mandibular incisors and not obvious on the mandibular incisors and premolars.3. In the early stage of treatment, the content of Fusobacterium nucleatum dose not change significantly.4. Real-time quantitative PCR is a rapid, accurate and effective quantitative analysis method for pathogenic bacteria and total bacteria number detection of patients'plaque with fixed appliance.